JP-A-2000-222659 shows an emergency report device for a vehicle. The emergency report device sends an emergency report signal to a service center, for example, when an airbag is inflated. In the above device, when a supply voltage of a main battery becomes lower than a predetermined threshold value, a power source is switched from a main battery to an auxiliary battery in order for an emergency report operation to be performed reliably. The power source supplies an electric power for energizing the emergency report device.
During the main battery normally supplies the electric power to the emergency report device, the auxiliary battery typically does not supply the electric power, according to the usage of the auxiliary battery. However, the auxiliary battery needs to supply the electric energy reliably when the main battery can not normally supply the electric power to the emergency report device. Therefore, it is necessary to perform a regular or periodic operational check of the auxiliary battery. The operational check of the auxiliary battery may be performed, for example, based on a current from the auxiliary battery. According to a related art, the operational check of the auxiliary battery is performed every time a vehicle drive mechanism starts or every time an IG signal is turned from an off state to an on state.
When the auxiliary battery as a primary battery is not rechargeable, the auxiliary battery needs to have a large current capacity so as to ensure the electronic power for starting the vehicle drive mechanism many times. However, in the above-described case, a manufacturing cost may increase. Further, a vehicle weight would increase, and the increase in the vehicle weight would cause a negative influence on fuel-efficiency.
It would be required for an emergency report device to perform an operational check of an auxiliary battery appropriately. It would be also desirable for an emergency report device that can be energized by an electric power from an auxiliary battery having a small current capacity.